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A 2.4- GHz Narrowband MEMS-Based Radio David Ruffieux, J´er´emie Chabloz, Matteo Contaldo, and Christian C. Enz
Abstract This chapter presents an innovative wireless transceiver architecture that rely on MEMS components to achieve further miniaturization and significant power dissipation reduction compared to low-power radios targeting LDR to MDR applications. It is shown in particular how the limitations of MEMS devices can be waived at the architectural level and how their combination can lead to innovative concepts preserving or even surpassing the performances of current mainstream optimized solutions. Besides the architectural aspects, the chapter also focuses on the design of some ultra-low-power and MEMS-specific circuits and reports measurement results of the complete system. The synthesizer, which is based on a low-phase-noise fixed-frequency BAW DCO and a variable IF LO obtained by fractional division from the RF carrier, achieves a phase noise of −113 dBc/Hz at 3 MHz. To correct for its ageing and thermal drift, the BAW DCO can intermittently be phase locked to a 3- µA, ±5-ppm, 32- kHz reference, which is obtained after temperature-dependent fractional division of the signal of a 1- MHz silicon resonator so as to compensate the non-idealities of the latter (frequency tolerance, large thermal drift). An all-digital PLL implementation guaranties a nearly immediate synthesizer settling when returning from an idle period, owing to the memorization of the previous lock conditions eliminating a multi-MHz XTAL and its associated start-up time. A sensitivity of 87 dBm was obtained in receive mode at 100 kb/s for a global consumption of 6 mA. The transmitter demonstrates a high-data-rate quasi-direct 1-point modulation capability with the generation of a 4-dBm, 1-Mbps, GFSK signal with an overall current of 20 mA. Both the receiver and transmitter further take advantage of BAW filters to implement interferers, image, and spurious rejection.
D. Ruffieux () • J. Chabloz • M. Contaldo • C. C. Enz CSEM, Centre Suisse d’Electronique et de Microtechnique, Neuchˆatel, Switzerland e-mail: [email protected] C.C. Enz and A. Kaiser (eds.), MEMS-based Circuits and Systems for Wireless Communication, Integrated Circuits and Systems, DOI 10.1007/978-1-4419-8798-3 10, © Springer Science+Business Media New York 2013
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D. Ruffieux
10.1 Introduction Miniaturization and reduction of the power dissipation are the main issues that currently prevent the seamless integration of wireless and networking capability into any tiny device used in short distance wireless applications. The latter include lowdata-rate (LDR) (typically 10 kb/s) applications such as wireless sensor networks (WSN), wireless body area networks (WBAN) but also medium-datarate (MDR) (typically 1 Mb/s) wireless applications such as audio streaming, wireless medical devices, wireless miniature drug delivery systems, or wireless implants. Today, both LDR and MDR use different radios that are individually optimized for each application. Nevertheless, t
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